Modeling layered crystal growth at increasing supersaturation by connecting growth regimes

Abstract

Mechanistic modeling facilitates rational crystallization engineering and design space screening. For an accurate model, the dominant growth mechanism operating on each face must be determined, which is highly dependent on supersaturation. Considering the case of centrosymmetric growth units, we developed and connected existing mechanistic expressions for spiral and two‐dimensional‐nucleation growth regimes, through application of stationary nucleation rate theory. Our approach enables calculation of crossover supersaturations and forms a framework to model the specific mechanism operating on each face under given crystallization conditions. Increasing supersaturation can change the crystal morphology; as face families switch growth mechanisms, they may grow out of the steady‐state shape, or influence its aspect ratio. Application of the model to naphthalene, biphenyl, pentaerythritol and β‐HMX shows the ability to capture experimentally observed examples of such supersaturation‐dependent crystal habits. This methodology broadens the applicability of mechanistic crystal growth modeling to include higher‐supersaturation industrial processes. © 2017 American Institute of Chemical Engineers AIChE J, 63: 1338–1352, 2017

Transient modes of zeolite surface growth from 3D gel-like islands to 2D single layers

“…Monomer-by-monomer addition is a classical pathway that falls within one of three modes of growth that depend upon supersaturation (Supplementary Note 2 and Supplementary Fig. 17 ): spiral, layer-by-layer, and roughened growth 45 . Low supersaturation (near equilibrium) is reached at the end of zeolite synthesis where ex situ AFM images of zeolite surfaces are comprised of hillocks.…”

In situ imaging of two-dimensional surface growth reveals the prevalence and role of defects in zeolite crystallization

“…As supersaturation decreases, the value of R crit increases and 2D nucleation ceases in favor of layer generation from spiral dislocations (Fig. 2B), where each segment advances once reaching a critical length, L crit , resulting in crystal interfaces comprising stepped hillocks (39,40).…”

Controlling the aqueous growth of urea crystals with different growth inhibitors: a molecular-scale study

“…(R,S)-alanine and g-glycine crystallizing from aqueous solution, the experimentally observed faster growing face along their polar axis can only be explained using a complex and distinct relay-type mechanism. 5 Nevertheless Tilbury et al 18 proposed mechanistic models that go well beyond the inhibition mechanism, and that can capture rough growth, 2D nucleation, and BCF spiral growth. On the computational front, Nielsen et al 19,20 investigated the attachment and detachment frequencies of solvated growth units to determine the rate of displacement normal to the face.…”